/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package studio.raptor.sqlparser.visitor.functions;

import static studio.raptor.sqlparser.visitor.SQLEvalVisitor.EVAL_VALUE;

import java.math.BigDecimal;
import studio.raptor.sqlparser.ast.SQLExpr;
import studio.raptor.sqlparser.ast.expr.SQLMethodInvokeExpr;
import studio.raptor.sqlparser.visitor.SQLEvalVisitor;

public class Char implements Function {

  public final static Char instance = new Char();

  public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
    if (x.getParameters().size() == 0) {
      return SQLEvalVisitor.EVAL_ERROR;
    }

    StringBuffer buf = new StringBuffer(x.getParameters().size());
    for (SQLExpr param : x.getParameters()) {
      param.accept(visitor);

      Object paramValue = param.getAttributes().get(EVAL_VALUE);

      if (paramValue instanceof Number) {
        int charCode = ((Number) paramValue).intValue();
        buf.append((char) charCode);
      } else if (paramValue instanceof String) {
        try {
          int charCode = new BigDecimal((String) paramValue).intValue();
          buf.append((char) charCode);
        } catch (NumberFormatException e) {
        }
      } else {
        return SQLEvalVisitor.EVAL_ERROR;
      }
    }

    return buf.toString();
  }
}
